runoffgroove whisker Biscuit

[arawn]

ok I built the runoff groove whisker biscuit finished the off board wiring tonight and I can't get it to work I used the 3pdt wiring scheme from here
and this scheme
I cxan't even get the led to light up what is going on??

[foxfire]

try this, http://www.aronnelson.com/gallery/v/DRAGONFLY-LAYOUTS_0/The-Mod-Zone-_/EZ_3PDT_WIRING.gif.html. if i'm not mistaken the lugs want to horizontal not vertical.

[arawn]

thanks I got it to light up and make noise  now i just have to figure out why i have such a small range on the volume??
I bought an alpha 100k audio taper pot but it has 2 sets of lugs and does not push/pull or anything straight audio taper only. I only have a useable range of about 20 degrees on it, and that is in the middle of it's range. If i turn it all the way either way it goes dead. I only used one set of lugs and otw followed the pcb schematic for this circuit, the only alt part i used was a .047 uf in place of the .033 spec'ed on the tone circuit.  

[foxfire]

my guess is you just need to get the right pot. it sounds like you have a dual gang pot. you may want to double check that the transistors are in correctly also. and don't worry, this pedal sounds pretty damn good so however long it takes it'll be worth it.

[DiamondDog]

thanks I got it to light up and make noise  now i just have to figure out why i have such a small range on the volume??
I bought an alpha 100k audio taper pot but it has 2 sets of lugs and does not push/pull or anything straight audio taper only. I only have a useable range of about 20 degrees on it, and that is in the middle of it's range. If i turn it all the way either way it goes dead. I only used one set of lugs and otw followed the pcb schematic for this circuit, the only alt part i used was a .047 uf in place of the .033 spec'ed on the tone circuit.  

FWIW, I did their perf build and specs. I only use about 20% of the volume pot range- the first 20%....  I included their tone control mod with the extra resistors and 50k pot that's on the schem.

Dual gang pot with noise only in the middle? You sure you've got the right pot?

[arawn]

Yeah I got it straightened out today lot of bashing through things before i thought to look at the wiring to the pot. I got the wires all crossed up and on the wrong lugs. i got it all straight now and yeah it sounds awesome. definitely worth the work!! And I seem to the volume all the way up myself 

[foxfire]

glad to hear you got it working! i think of it as a big muff for someone who likes to do leads.

[Mark Hammer]

Resurrected this because I wanted something that could fit in a 1590B with three control holes drilled in it.

Stock, I find it much too intense, and the tone control is just way too woolly at the bass end and mosquito-like at the treble end.

I changed the bass cap from 33nf to 18nf and the treble cap from 4n7 to 6n8.  I changed the feedback cap on the output transistor from 47pf to 180pf.  Doing all of that yielded a much smoother sound, less hiss and tone settings that were far more usable at the extremes.

Finally, because I had a 3rd hole in the enclosure, I wanted a variable gain control.  Instead of tying the Q2 emitter to ground, I connected it to a 1k pot, used as a variable resistance to ground.  At min resistance, it is the stock intensity, and at 1k resistance it behaves more like an overdrive.  Never gets "clean", even with reducing guitar volume.  But if I wanted clean, I wouldn't be running it through this circuit.

Transistors were as one sees posted: a pair of 2N5088s and an MPSA13.  I used the layout posted on the ROG site from Pablo De Luca.

Smart, simple, cost-effective circuit.  To my ears, does all the tricks of a BMP.

[Andon]

Thank you for reviving this thread and, thus, making me privy to this design - definitely gonna' have to give it a try!

[Mark Hammer]

My pleasure.  It's NOT going to change your life, but I find it's a very good return on investment, in terms of parts and build time.

One additional note.  Listening more closely, and perhaps a function of the specific transistors I used, but at max gain and max treble, the hiss may be objectionable to some.  If you stick a small-value resistor between the Q2 emitter and 1K pot (e.g., 33-47R), that will let you turn the gain up full without having to worry about hiss.  It may also be a good idea to increase the value of the feedback cap in Q1 from 47pf to 100pf.

[Andon]

Bumping this thread again right quick to ask that since the signal is being taken from the collector of each transistor stage (including the darlington transistor setup) that would make this a non-inverting pedal, is that correct?

[antonis]

Any single common emitter amp is inherently inverting..
(odd number of the above result into inverting circuit where even number result into non-inverting circuit..)

[Andon]

Ah, okay, I had read that it depended on whether the signal came off of the collector or emitter, but had also read that you could count the number of transistor stages to figure it out too. So does the fact that a darlington is essentially two transistors into each other change that?

[antonis]

When signal enters into Base it can either come out of the Emitter (in phase / voltage follower / Common Collector configuration) or out of the Collector (180^o out of phase / inverted / Common Emitter configuration)
Common Base is another configuration where signal enters into Emitter and comes out of the Collector..
(you can realize that "common" transistor leg doesn't deal with signal input/output..)

Darligton (or Sziklai) pair is considered as a single device so it also falls into above configurations..
https://sound-au.com/articles/cmpd-vs-darl.htm

[Andon]

Looks like I had it backwards - thank you very much for clarifying!